﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using LinFu.IoC.Interfaces;
using LinFu.IoC;
namespace CoreEx.Common.Extensions
{
    public static class StringExtensions
    {
        private static IServiceContainer _serviceContainer = Services.ServiceLocator.Container;
        private readonly static IPluralizer _pluralizer;

        static StringExtensions()
        {
            _pluralizer = _serviceContainer.GetService<IPluralizer>();
        }

        /// <summary>
        /// Compute the Levenshtein Distance between two strings.
        /// </summary>
        /// <param name="s">The first of the two strings you want to compare.</param>
        /// <param name="t">The second of the two strings you want to compare.</param>
        /// <returns>The Levenshtein Distance (higher is a bigger difference).</returns>
        public static int ComputeDistance(this string s, string t)
        {
            int n = s.Length;
            int m = t.Length;
            int[,] d = new int[n + 1, m + 1]; // matrix

            // Step 1
            if (n == 0)
            {
                return m;
            }

            if (m == 0)
            {
                return n;
            }

            // Step 2
            for (int i = 0; i <= n; d[i, 0] = i++)
            {
            }

            for (int j = 0; j <= m; d[0, j] = j++)
            {
            }

            // Step 3
            for (int i = 1; i <= n; i++)
            {
                //Step 4
                for (int j = 1; j <= m; j++)
                {
                    // Step 5
                    int cost = (t[j - 1] == s[i - 1]) ? 0 : 1;

                    // Step 6
                    d[i, j] = Math.Min(
                        Math.Min(d[i - 1, j] + 1, d[i, j - 1] + 1),
                        d[i - 1, j - 1] + cost);
                }
            }
            // Step 7
            return d[n, m];
        }
        
        public static string GetBestMatch(this string value, IEnumerable<string> candidates)
        {
            return candidates.OrderBy(c => ComputeDistance(value, c)).First();
        }

        public static string ToPlural(this string singularNoun)
        {
            return _pluralizer.ToPlural(singularNoun);
        }

        public static string ToSingular(this string pluralNoun)
        {
            return _pluralizer.ToSingular(pluralNoun);
        }

        /// <summary>
        /// Strips of the formatting (new line and tabs) 
        /// </summary>
        /// <param name="target">The target string.</param>
        /// <returns><see cref="string"/></returns>
        public static string Strip(this string target)
        {
            return target.Replace(Environment.NewLine, "").Replace("\t", "");
        }
    }
}
